Circuit element and motor for driving the same



Jan. 25, 1949. E. G. SEATH ET AL CIRCUIT ELEMENT AND MOTOR FOR DRIVINGTHE SAME Filed July 25, 1944 2 Sheets-Sheet 1 A [Inf/Icy Jan. 25, 1949.E G SE TH ET AL 2,459,844

CIRCUIT ELEMENT AND MOTOR FOR DRIVING THE SAME Filed July 25, 1944 I 2Sheets-Sheet 2 '[nve ntors Emma QRRHRM SEXY Evwm Cmqa KLEPP B y WW7 l Altorney Patented Jan. 25, 1949 UNITED STATES PATENT OFFICE CIRCUITELEMENT AND MOTOR FOR DRIVING THE SAME company Application July 25,1944, Serial No. 546,534 In Great Britain July 29, 1943 '7 Claims. 1

The present invention relates to remote control tuning arrangements forelectrical circuits and concerns more particularly means for tuningradio transmitting and receiving sets and the like from a distant point.

Radio receiving sets used in aircraft often have to be located at somepoint out of reach of the operator, and it is at the same time necessary to provide means whereby the operator may tune such a set withoutleaving his seat. In particular it is often necessary for him to be ableto tune the set, and to transmit or receive messages on severaldiiferent wavelengths in the course of a flight.

There are, of course, a number of well known electrical arrangements forthe remote tuning of a radio set. One class of such arrangements makesuse of an electric motor driven from a source of supply available in theset and controlled from the distant point over appropriate conductors.This motor is geared to an adjustable tuning element, such as aninductance or condenser, and drives it in the appropriate direction,being automatically switched off at the right moment depending on thesetting of the control at the remote point.

This arrangement is often complicated, especially if accurate tuning isdesired, and the object of the present invention is to provide a muchsimpler electrical arrangement by which accurate tuning adjustments maybe made from the distant point, and which behaves substantially as ifthere were a direct mechanical connection between the tuning element andthe control.

The invention consists in applying to the problem one of the remoteindicating or telemetering systems such, for example, as the systemknown by the registered trade-mark Desynn in which a rotatable shaftconnected to the armature of a local motor follows the movements of asimilar rotatable shaft forming part of a control device or remote unitconnected by wires to the motor.

The invention accordingly provides an arrangement for the remoteadjustment of an electrical circuit element, for example, a condenser,comprising a rotatable shaft connected to the said element, a localmotor having a plurality of windings and adapted to control the movementof the said shaft in accordance with the distribution of currents in thesaid windings, a F

control device at a distant point, and means controlled by the saiddevice for supplying currents to the said windings distributed in amanner characteristic of the position of the said device.

The shaft of the remote unit or control device may be provided with amanual control knob and dial plate, if necessary, in any suitable way.The dial plate may be marked with a scale in capacity or Wavelengths orthe like, and the control of the tuning is precisely as though thecontrol knob were mounted in the usual way directly on the radio set orother apparatus containing the adjustable circuit element. Thus there isno lag or delay such as would be produced by the tuning motor in theknown arrangement already mentioned, and no complicated circuitarrangements are required to ensure the necessary accuracy of tuning.

The Desynn remote indication system is operated by direct currents;other known systems employ alternating currents. Either type of systernmay be employed for the present invention according to the availableelectricity supply, though the direct current system is preferred forreasons which will be explained later on.

The invention will be explained in detail with reference to the drawingsaccompanying the provisional specification, in which:

Figs. 1 and 2 show diagrammatically the known direct and alternatingcurrent remote indication systems;

Fig. 3 shows a section view of a remotely adjustable tuning condenser,according to the invention; and

Fig. 4 is a view of the base of the condenser shown in Fig. 3.

Fig. 1 shows a schematic circuit of the direct current remote indicationsystem, and Fig. 2 shows that of the alternating current system.

Referring first of all to Fig. 1, the local motor is diagrammaticallyshown and comprises a stator I having a three phase winding, and a rotor2 which consists of a permanent magnet N'S carried. on a shaft shown insection at 3.

The remote unit at the distant point comprises a complete circularevenly wound resistance winding 4, provided with a pair of insulatedcontactors mounted on an arm 5 carried on a rotatable shaft shown insection at 6. The two contactors make contact at diametrically oppositepoints of 'the resistance winding 4, and are respec tively connected tothe terminals of a suitable direct current source, represented as abattery I.

The three delta or star terminals of the winding I are respectivelyconnected by three corresponding conductors 8 to three points on thewinding 4 spaced 120 degrees apart.

When the arm 5 is set in any position, the potentials appliedindividually to the conductors I! will be characteristic of thatposition, and will produce a corresponding distribution of currents inthe stator l. A resultant magnetic field having an orientationcorresponding to thatof the arm is thus obtained, and the magnet NS willassume the same orientation. If the arm 5 is rotated through any angle,then the rotor 2 willbe rotated through the same angle.

In Fig. 2 is shown the corresponding alternating current system. In thiscase the remote unit and local motor are identical.

They comprise respectively stators QT and 9B. each having three phasewindings and rotors IT and IUR each having a single phase winding. Bothrotors are supplied in parallel with single phase alternating current,and the delta or star points of the stators are respectively connectedtogether by three conductors II.

The rotors are carried on respective rotatable shafts shown in sectionat IZT and IZR. When the rotor 1.0T is set in any position, a certaindistribution of potentials is induced in the windings of the stator 9Twhich produces a corresponding alternating magnetic field of fixeddirection in the stator 9R. Assuming that the rotor lllR has been placedin the position corresponding to this direction, it will be held thereand will thereafter follow exactly the movements of the rotor IBT. Ifpreferred, the three phase windings may be put on the rotors and thesingle phase windings on the stators.

The direct current system of Fig. 1 is preferred in the case of thepresent invention for the following reasons:

1. A much larger torque may be obtained at the receiver, other thingsbeing equal.

2. The direct current system requires only three. wires to connect theremote unit to the local'motor, instead of five as in the alternatingcurrent system.

If, however, a direct current supply is not available, the system ofFig. 2 may be employed.

According to the invention, the movable part of an adjustable tuningelement forming part of an electrical tuned circuit, such as is used ina radio set, is mechanically connected to the Shaft 3 in Fig. l (or HRin Fig. 2). The shaft 6 in Fig. 1 (or lZT in Fig. 2) carries a knob orother appropriate manual adjusting means, together with a scale plate orthe, like, if desired. On rotating the knob, the movable part oftheftuning element follows as though the two were joined by a directmechanical coupling.

The movable part of the tuning element may, for example, be therotatable vanes of an air condenser. or a movable dielectric; or it maybe rotatable coil for a variable inductance, or an adjusta-ble. core.

In Fig. 3 is shown one embodiment of the incoupled to the spindleZBcarrying the movable plates of the condenser 20, a central clearance11016.29 being provided on the base plate to allow the shaft 23 to passthrough. The terminals oi; thermotor andcondenser are carried on asecond insulating plate 30, and may be arranged in the same way as inthe well known Octal type of valve base, as indicated in Fig. 4. Theplate 353 is fixed to the plate 2| by metal rods 32.

Of the eight terminals 3i shown, only six are required. Of these, threemay be used for the delta points of the stator winding, one each for thetwo sets of fixed plates of the condenser 29, and one for the movableplates. Connections to these terminals may be made in any convenientway.

The local motor and condenser are shown totally enclosed in a metal case33 which is fixed to the plates 2! and so. This can act as anelectrostatic screen and if desired may be filled with a suitableinsulating oil. This oil serves to protect the unit from moisture, todamp the movements of the rotatable parts, and to increase the capacityof the condenser. In order to allow for thermal expansionandcontraction, the case may be formed into bellows 34 as indicated. Avent 35 is mounted in the plate 38. This is for the purpose ofexhausting the case and subsequent filling with oil, after which thevent may be closed by means of a screw 35 and sealed with solder. Thevent may also function as the central pin of the octal type base.

The external diameter of the case 33 may be under two inches, and thatof the motor 22 may be perhaps 1 /3 inch. It'will, therefore, be seenthat the whole unit may be extremely compact and may be mounted in theradio set or other apparatus exactly like a small thermionic valve, andit will take up about the same space.

The local motor 22 is preferably of the type described and claimed inany of the British Patent Specifications Nos. 529,583, 537,833, or545,730. It may, however, take any other desired form, and if thealternating current system described with reference to Fig. 2 is used, asuitable local motor may be mounted and coupled to the condenser in amanner similar to Figs. 3 and 4.

It will. be evident that instead of a condenser. a variable inductancecould be mounted ina similar manner with a rotatable coil or movablecore coupled to the shaft .23. If desired, also. appro priate gearing orthe like could be introduced so that the adjustable member might beindirectly driven from the shaft 23, possibly at a dliierent speed.

The remote unit shown in Fig. 1 consists of circular resistancepotentiometer and can be provided in any well known way. In the case ofthe alternating current system the remote unit can be a duplicate oi thelocal motor and the manual labor control knob can be coupled to it inany suitable manner.

It be added that in automatic tuning arrangement-s in which a radioreceiver is in tune by means of the received signal, a discriminatorcircuit or the like may be for ex" ample, to produce a voltage dependingupon the departure of the resonance frequency of the tuned circuit fromthe si, .211 frequency. This voltags is employed. to r adjust thecircuit. The arrangement of the present invention provides a convenientmeans for enabling the above mentioned voitage to control an element ofthe tuned circuit by causing it to act upon the local motor so as toadjust the element in the manner described. In this case, discriminatoror other arrangement-takes the place of the remote unit. Y

5 What is claimed is:

1. Device for the control of the angular position of a rotatableelectrical circuit element, including a rotatable shaft connected tosaid circuit element, a motor of the type having a plurality of windingsand a rotor cooperating therewith to control the movement of said shaftin accordance with the relative distribution of currents in saidwindings, and a single terminal plate common to both said motor and saidcircuit element.

2. Device according to claim 1, also including means for damping themovements of said circuit element, comprising a liquid surrounding atleast the rotatable portions thereof.

3. Device according to claim 1, wherein are also provided chamberedmeans in which said circuit element and motor are enclosed, saidchambered means comprising a unitary sealed envelope, and said singleterminal plate comprising a unitary structure capable of beinginterchangeably plugged in and out of circuit.

4, Device according to claim 1, in which said circuit element is arotatable condenser, and in which is provided a liquid surrounding saidcondenser and acting as a damping medium, while also serving as thedielectric for said condenser,

5. Device according to claim 1, likewise including an envelope enclosingsaid circuit element and said motor, a combination damping anddielectric liquid within said envelope, and an expansibleliquid-confining member forming at least a portion of the parietal partof said envelope, whereby thermal expansion of said liquid causes saide'xpansible member to maintain within said en- 6 velope a plenumcondition, with respect to said liquid, when the circumambienttemperature of said device is changed.

6. Device for the control of the angular position of a rotatableelectrical circuit element, including a rotatable shaft connected tosaid circuit element, a motor of the type having a plurality of windingsand a rotor cooperating therewith to control the movement of said shaftin accordance with the relative distribution of currents in saidwindings, and a flexible housing common to both said motor and circuitelement.

7. Device for the control of the angular position of a rotatableelectrical circuit element, including a rotatable shaft connected tosaid circuit element, a motor cooperating therewith to control themovement of said shaft, and a flexible housing common to both said motorand circuit element.

EDWARD GRAHAM SEATH. EDWIN CLAUDE KLEPP.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,289,898 Phillips Dec. 31, 19182,038,059 Reichel et al Apr. 21, 1936 2,184,347 Jewell Dec. 26, 19392,269,602 Reichel Jan. 13, 1942 2,295,442 Wilhelm Sept. 8, 19422,321,699 OBrien June 15, 1943

